Servers/MoonlightServers.Daemon/ServerSystem/Implementations/Docker/DockerEventService.cs

using Docker.DotNet;
using Docker.DotNet.Models;
using MoonlightServers.Daemon.ServerSystem.Implementations.Docker.Events;

namespace MoonlightServers.Daemon.ServerSystem.Implementations.Docker;

public class DockerEventService : BackgroundService
{
    public event Func<ContainerDieEvent, Task>? OnContainerDied;

    private readonly ILogger<DockerEventService> Logger;
    private readonly DockerClient DockerClient;

    public DockerEventService(
        ILogger<DockerEventService> logger,
        DockerClient dockerClient
    )
    {
        Logger = logger;
        DockerClient = dockerClient;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        Logger.LogTrace("Starting up docker event monitor");

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                Logger.LogTrace("Monitoring events");

                await DockerClient.System.MonitorEventsAsync(
                    new ContainerEventsParameters(),
                    new Progress<Message>(OnEventAsync),
                    stoppingToken
                );
            }
            catch (OperationCanceledException)
            {
                // ignored
            }
            catch (Exception e)
            {
                Logger.LogError(e, "An error occured while processing container event monitoring");
            }
        }

        Logger.LogTrace("Closed docker event monitor");
    }

    private async void OnEventAsync(Message message)
    {
        try
        {
            switch (message.Type)
            {
                case "container":

                    var containerId = message.Actor.ID;

                    switch (message.Action)
                    {
                        case "die":

                            if (
                                !message.Actor.Attributes.TryGetValue("exitCode", out var exitCodeStr) ||
                                !int.TryParse(exitCodeStr, out var exitCode)
                            )
                            {
                                return;
                            }

                            if (OnContainerDied != null)
                                await OnContainerDied.Invoke(new ContainerDieEvent(containerId, exitCode));

                            return;
                    }

                    break;
            }
        }
        catch (Exception e)
        {
            Logger.LogError(
                e,
                "An error occured while handling event {type} for {action}",
                message.Type,
                message.Action
            );
        }
    }
}